The proposed project studies the etiology, course, and consequences of substance use and substance disorders from a developmental perspective in a high risk sample. In so doing, it addresses a centrally important question in substance use research-namely, what are the etiological pathways by which risk is transmitted across multiple generations? We predict heterogeneity in trajectories of substance use outcomes among children of alcoholics and controls, identify mediating mechanisms underlying familial alcoholism risk, and examine emergin, risk in the next generation using a multi-method prospective study. To achieve these aims, we capitalize on a unique multigenerational high risk sample that spans the ages from 'substance use initiation to the development of substance use disorders and adult "maturing out," and for whom data (have already been collected from three generations (G1-G3). The sample includes alcoholic mothers and fathers whose alcoholism and other disorders were directly ascertained. Beginning in adolescence (M=12.7 years), G2s and) their parents had 3 annual assessments. Further follow-ups (adding full biological siblings and peer informants) were) !done in late adolescence (Wave 4) and early adulthood (Wave 5). Wave 5 also added a baseline multi-method [assessment of the G3 children (mean age=7.4). At the proposed follow-up, computer-assisted interviews will be conducted with G2 adults, their G3 adolescent] children, and the G3 adolescent's other parent. Other informant data (peers for adults and teachers for adolescents) (along with school records data will be collected by mail. G3 adolescents will also perform standardized tasks assessing executive and motivational regulatory processes. A short-term 18-month longitudinal design allow; respective prediction of G3 adolescent substance use from existing baseline data as well as the newly proposed assessments. The findings are particularly important for prevention because they focus on a high risk group, they track the natural history of substance use from its precursors to clinically important end points, they include Potentially modifiable factors, and they examine the transmission of risk across three generations.